Originally Posted by chronisb
I am building a new dedicated HT in a 17x13 room in the basement (one entry door to room, no windows, 9" ceilings) . I am considering doing Beta 50s for fronts and rears because the price difference between the 50s and the
20s is nominal, so I figure go large all the way around. Does anybodyd have a good reason that this would be a bad idea? Thanks
To most accurately produce soundtracks in surround it is always best to emulate the way speakers are set up in a THX-approved movie theater. That is, left and right surround speakers are placed on the sidewalls, not the rear walls of the theater. And that the side-mounted left and right surround speakers fire Over, Not At
the seated listeners. Rear surround speakers in a movie theater, those which produce the sixth channel encoded (in mono) on some DVDs, are mounted on the rear walls of the movie theater. The surround rear channels of a THX-approved theater also fire over not at
the ears of the seated listeners.
Contrary to popular belief, virtually all primary vocal information in both two and three-way loudspeakers designed for the home comes out of the woofers, not the midrange or tweeter. It is the harmonics of the human voice (usually above 800Hz or so) which are usually produced by the midrange. In the Beta 40s and 50s I chose 850Hz as the crossover point between the woofer and midrange.
IMHO the only time all speakers, both LCRs and surrounds should all be placed at ear level is:
a) if you listen exclusively to surround vocals in music tracks (which have no video) or
b) if you are the actual mix-down engineer on a sound stage and you need to hear (directly) the surround immersion effects your are trying to create for a movie.
In playback mode, the mode in which we as consumers of movies and music listen, the primary intent of the LCRs is and always has been Localization
of the sounds. Whereas for surrounds
, whether sides or rears the primary intent is and always has been Envelopment (or Immersion).
To make the intent of an effect most believable surround speakers should always
be placed above the level of the heads of seated listeners. The reason for this is that our ear-brain sense of direction is not so good to the sides and the rear if the sounds are not coming directly at our ears but instead slightly above (18” to 24” for most home theaters) our ears. This is when the immersion effect works best at tricking our brains into thinking that we are “surrounded-by-sound”.
Interestingly this “above the head placement” does Not mean that surrounds should be mounted in the ceiling. Ceiling-mounted speakers mess with the HRTF (head related transfer function) in our brain. Simply put, this means that, by their very placement, ceiling-mounted speakers allow both ears to hear, say an effect coming from the right speaker. This totally messes up the intended channel separation of the effect (since we can now hear the effect with both ears instead of just our right ear. Why? Because when surround speakers are positioned properly, 18” to 24” above the seated listener’s head, it is one’s own head which blocks the left ear from hearing the sound
(the so-called HRTF). This is why THX theaters are always set up with the side and rear surrounds firing Over the heads of the seated listeners in the theater audience. And why such placement practice in the home can be such big dividends (by more accurately creating the sense of envelopment).